This invention relates to estimation of device operating temperature in processing a signal, and more particularly to use of indirect methods to estimate such temperature.
Ideally, operating temperature for processing of a digital signal by a device, such as a gate, is constant and within the parameter range(s) assumed in the digital design. Practically, the operating temperature associated with signal processing by a given device can vary with time, depending upon the present circumstances and recent history of operation of the device. If the device temperature varies too much from the assumed idealized value, undesirable device responses, such as device malfunction or operation in an undesirable regime, can occur. This is especially true for device temperature that exceeds a threshold temperature value. Inclusion of a system that directly measures such operating temperature is an attractive spectre but is likely to result in an external measure that is too complex, too expensive or too slow acting to fulfill the original function(s) of the device.
What is needed is an approach that uses an indirect method to unobtrusively estimate device operating temperature in a manner that does not interfere with or retard operation of the device and does not add substantially to the complexity or cost of the device. Preferably, this approach should be capable of estimating whether the associated device temperature is above or below a threshold value (yes/no) and should be capable of providing a more precise numerical estimate of the associated device temperature, where such estimate is needed.
These needs are met by the invention, which provides a system and method for indirectly estimating the operating temperature associated with processing of a digital signal by a digital device. In one embodiment, the invention monitors device time delay to indirectly estimate the device operating temperature, by comparing the time delay of a signal processed by a sample device, such as a gate, with an acceptable time delay for the sample device. Device operating temperature T tends to rise monotonically and continuously with increasing device time delay xcex94td, although the quantitative details will vary from one type of device to another.